Due to the development of communications systems, various types of user equipments have been introduced to consumers, both organizations and individuals. Current mobile communications systems belonging to the 3rd generation partnership project (3GPP) family, such as long-term evolution (LTE) and LTE-Advanced, are high-speed and high-capacity communications systems that transmits various types of data, such as images and wireless data. Such high-speed and high-capacity communications systems require a technology for transmitting a large amount of data at a high speed as fast as that of wired communications networks. For transmitting high-capacity data, a plurality of cells may be used to efficiently transmitting data.
However, there are limitations, in that a base station allows a plurality of user equipments to transmit large-capacity data, using limited frequency resources. That is, it may be relatively expensive for a specific service provider to ensure frequency resources for exclusive use, which is problematic.
In addition, a plurality of providers or communications systems can share unlicensed frequency bands that a specific provider or a specific communications system cannot exclusively use. For example, wireless local area network (WLAN) technology represented by Wi-Fi provides data transmission/reception services using unlicensed frequency resources.
Thus, for mobile communications systems, it is required to develop technology for transmitting and receiving data to and from user equipment using Wi-Fi access points (APs). In particular, when a base station transmits and receives data to and from user equipment using Wireless resources of WLAN and wireless resources of a base station, it is required to develop specific procedures and methods regarding such data transmission and reception.